This invention relates to a process for preparing a lubricated water-soluble vitamin powder. Particularly useful water-soluble vitamins used to make the powder are ascorbic acid, sodium ascorbate, and calcium ascorbate. The lubricated powder is directly compressible into tablets and is resistant to demixing. 2. Description of the Prior Art
It is known to prepare water-soluble vitamin powdersbby spray drying a water-soluble vitamin with various excipients such as a binder and an adsorbent. The prior art also teaches that a lubricant needed for tableting can be manually blended with the powder. See for example U.S. Pat. No. 3,293,132.
The prior art, however, does not teach that the lubricant is combined with the water-soluble vitamin powder at a temperature which is sufficient to melt the lubricant. This modification provides powders which are resistant to demixing. Demixing is undesirable because it results in a non-uniform distribution of the lubricant in the powder. Moreover, the prior art does not teach that a lubricated powder can be prepared by a continuous process which is the case when a powder is prepared by spray drying and then passed through a continuously operated fluidized bed at a temperature sufficient to melt the lubricant.